Safety valve for hydraulic brakes



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` March 7, 1939. H, CgcaN 2,149,295

` y SAFETY VALVE FOR HYDRAULIC BRAKES v Filed Nov. 27, 1957' illimite Patented' Mar. l7', 1939 I I UNITED STATES PATENT.

2,149,295 A snm vALvn Foa immaturo Blanes John n. Jonson,

HentonqAla.

Application November zr, 19:7, ser-arm. 11am s claims. (ci. soa-s4) v the casing are partitions I and l providing com'- j 'Ihis invention relates to and has for its primary safety device for for automobiles,

In the operation sometim happens iiuid pressure brakes object to provide a use with hydraulic or air brakes trucks.' etc.

of iluid pressure brakes it that a leak is caused in a line leading to one or more of the brakes.

Such due to the fact that are operated from the a leak in'any one of cylinders will therefore renderthe .entire braking system of the vehicle ineiective. which might easily result the braking system, the for its object to whenever a leal;l

A further'object of the the. provision in a safety Other objects and advan will be .apparent from the when taken in connection ing drawing in which,

To avoid serious accidents from such failure oi present invention -has provide an automatically opinvention resides in attachment as above tages ot the invention following description with the accompanysection, showing the sentinel valve and Figure 3 is latching elements.

men-mg in die drawing a perspective view of one or the in detail, the numeral l indicates generally a system of valves vfor use in shutting oit a plurality oi'brakes in a branch line extendin will be understood that four both rear brakes, then a branch line to one `or iluid braking system.

single brake thenv it only two of the mechanisms would be installed. Since the mechanisms are duplicates a disci suillce lhe'casing 'I is provided 'I for the attachment of i osure of one of them will with apertures! and niet and outlet pipes respectively, leading from the source of iluid supply and to Aone or more brakes, as the case -v u be. Extending transverse v ml! ly ci' the interior of to form a latch element for partments l, l and I.

Mounted in threaded openings formed in the partition I is a pair oi.' apertured plugs or valve seats t and Il. a valve stem II on which is slidably mounted a disc valve Il, and acoil spring I3 normally holds the valve in position to close the passages in the plug l. .A nut Il is threaded on the 'upper end of stem II .andprovidesl Ior'adJUsting the spring .prsure on the valve. The spring of this valve is preferably of tain ten pounds working pres/sure in compart ment 1, and automatically opens to allow the escape of iiuid whenpressure on the brake pedal is removed. The casing I is provided with a closure Il directly above valve I2 access to the adjusting nut Il.

'Cooperating with valve seat I0 is a valve I6, opening in the direction if ilow through the casing, and provided vwith a stem Il extended upwardly through the plug. A coil spring I8 is mounted on the valve stem Il and a nut 'Il 'threaded on the upper end of the stem servesv to adiust the pressure on the valve. Access to this valve may be had through closure 2l.

Mounted in the lower partition l is an apertured plug or valve scatti provided with a disc valve 2! opening in a direction agaimt the ilow of iluid. The valve 22 is provided with a stem 2l extending downwardly through seat 2| and a coil spring 2| tending to pull to its seat. An adjusting nut 2 the lower end o'f the valvefstem. Access to the nut 2i may be had through closure 2l threaded into the lower end of the casing.

'The valve stem -23 is extended upwardly beyond valve 2! and has its upper end slidably received in a downwardly-extendingr pocket 21 formed on partition I. This member is provided withaanother latch element to be described.

ng laterally from themain body of the casing I and communicating with the chamber 'I thereof is a cylinder 29 provided with a piston Il.' The outer end of this cylinder is closed by a threaded member 3i which is in turn Provided with a threaded bolt 32. A lock nut J3 is mounted on bolt 32, and the opposite or inner end -of the bolt is provided with a seat or bearing Il for one end oi' a coil spring 35. 'I'he opposite end of spring 3S is in engagement with the piston Il and tends to move it to the right as viewed in Flaute l.l This piston is provided with The valve seat 9 is provided with to permit cooperation withl cient strength to r'e- `a rubber cup or disc 36 to prevent leakage, and

'j' a tripping plunger 31 has its head 38 in engagei 39.' The plunger ment with the disc.

The opposite end of plunger 31, which is formed with a slotted section 39, is fixed in a head 40.

This head is slidably mounted in a cavity formed in the/inner face of a closure 4l, and a spring l2 mounted in the cavity is of suilicient strength to bias the head toward the left (Fig. 1) and maintain the head 33 in contact with the piston cup 36.

As will be obvious from a comparison of Figures '1 and 2 the valve 22 is held in open position by the tripping plunger 31 until such time as the plunger is moved to the right, at which time the spring 2l will move the valve onto its seat. Movement of the plunger 31 to the right is caused by spring 35, but is permitted only at such time as the pressure in compartment 1 is reduced below the normal working pressure. In order to reset the valve 22 after it has been closed a manually-operated plunger 50 is provided. This plunger is slidably mounted in the closure plug 26 and is normally retained in retracted position by means of a coilspring 5I disposed between the plunger head 52 and a portion of the closure 26. A screw cap 53 normally incloses the resetting' plunger and its spring.

In order that the operator of the vehicle may be warned by either a visual Whenevera leak occurs in the fluid pressure line an electrical circuit closer is provided. .This construction includes a contact 60 normally biased to the left (Fig. 1) by means of a spring 6 l. Adapted tocooperate with contact 60 is a contact 62 which is formed as an extension of the tripping plunger 31. The contact 60 is mounted in a fitting extending exteriorly of the closurev 4I and is provided with means for connecting an electric wire for signalling purposes. It will be obvious thereiore that when reduced pressure in the system allows the plunger. 31 to move to the right the contacts 60, 62 will be brought together thereby closing the electrical circuit and causing an operation of the signal.

The operation of the mechanism will now be described. f

The device having been installed and all air removed from'the system, if of the hydraulic type,

pressure is exerted on the brake pedal to exceed or pounds, the work pressure, thereby forcing the piston 36 and plunger 31 to the left. The enlarged head of the pin 2B limits the leftward movement of the plunger until the 4manuallyoperated plunger`50 is operated to lift valve 22 and bring the cut-away portion of pin 28 into the slot 31 then moves entirely to the left as indicated in Figure 1, and holds pin 28 and valve 22 in elevated position.

The braking system is now ready for operation and remains in operative condition until such time as a leak occurs'in one of the lines.- The escape of fluid from'the line to which the particular sentinel valveis attached will cause the pressure to drop below the ten pllnds working pressure andimmediately allows the spring 3d` to move the tripping plunger 31 to the right. This movement of the plunger will release the latch or pin 2t of valve 22 and allow spring 24 to move the valve kto closed position, thereby completely shutting off 1., the valve 22 of the line may be reset by operation of the plunger 50, and the entire braking system again placed in operative condition.

or an audible signal ing with the latch to From the foregoing description taken in connection with the accompanying drawing it will bev apparent to those skilled in the art that I have devised`a relatively simple and. inexpensive construction of sentinel valve for iiuid brakes that it is of strong and durable construction and reliable in operation; that it may be readily reset after the leak which caused its operation is repaired; and that it is well suited to the operation of a visible or audible electrical signal if desired.

In accordance with the patent statutes I have described what I now consider to be the preferred form oi construction, however, it will be apparent that various changes may be made in the structural details withoutdeparting from the spirit of the invention, and it is lintended that all such changes be included within the scope of the appended claims.

What I claim is: f

1. A safety valve mechanism for fluid pressure vehicle brakes, including a casing adapted to be mounted in a line leading toja brake, a valve for admitting pressure iluid to a compartment of the casing, Va spring-pressed valve for preventing the exit of pressure iluid from said compartment, and means for normally holding the second-mentioned valve inlopen position, said means including a pressure-controlled plunger.

2. A safety valve fmechanism for iluid pressure vehicle brakes,'including'a casing adapted -to be mounted in a line leading to a brake, a valve for admitting pressure fluid to a compartment of the casing, a spring-pressed valve for `preventing the exit of pressure fluid from said compartment, a reciprocably mounted plunger for normally holding the second-mentioned valve in open position, pressure-controlled means for moving the plunger to valve-holding position, and a spring for moving the plunger to releasing position.

3. A safety valve mechanism for fluid pressure vehicle brakes, including a casing adapted to be mounted in a line leading to a brake, a valve for casing, a spring-pressed valve .for preventing the exit of pressure iiuid from said compartment, a latch connected to the second-mentioned valve, a reciprocably mounted plunger normally cooperathold the valve in open position, pressure-controlled means normally holding.

the plunger in operative position, and means for moving the plunger to inoperative position.

4. A safety valve mechanism for fluid pressure vehicle brakes, including a casing adapted to be mounted in a line leading to a brake, a valve for admitting pressure fluid to a compartment of the casing, a spring-pressed valve for preventing the exit of pressure iiuid from said compartment,

a cylinder communicating with the compartment, a piston and plunger in the cylinder, means on the plunger for normally maintaining the lastmentioned valve in open position, and a spring for moving the plunger to valve-releasing position when the pressure in the cylinder is reduced beyond a predetermined amount.v v

5. A safety valve mechanism for uid pressure vehicle brakes, including a casing adapted to be mounted in a line leading to a brake,- a Valve for admitting pressure iiuid'to a compartment of the casing, a spring-pressed valve for preventing the exit of pressure iiuid from said compartment; a

" cylinder, communicating with the compartment,

a pistq'n and plunger in the cylinder, cooperating adapted to move the same to valve-holding position, a spring for moving the plunger to releasing after it has been closed.

7. A safety valve mechanism for uid p'ressure vehicle brakes, including a valve casing adapted l JOHN H. J OBSON .v 

